This invention relates to coated masonry building units, coating compositions therefor, unsaturated polyester resins, and the method of producing the coated masonry building units with a facing or coating that will be both stain-resistant and resistant to discoloration (blushing) when subjected to high moisture conditions for long periods.
There are disclosed in my prior patents:
A. U.S. Pat. No. 2,751,775, issued June 26, 1956 -- a coated masonry building block made of a cured composition of an unsaturated polyester resin and sand in which the sand comprises at least 50% by weight of the coating composition. The unsaturated polyester resin is derived from a reaction between a dicarboxylic acid, e.g., phthalic, maleic, fumaric, adipic, pimelic, suberic, sebacic, itaconic, citraconic and succinic acids and their anhydrides and a polyhydric alcohol, e.g., ethylene glycol, diethylene glycol, and propylene glycol.
B. U.S. Pat. No. 3,328,231, issued June 27, 1967 -- a coated masonry building block made of a cured composition of an unsaturated polyester resin as described in U.S. Pat. No. 2,751,775, and a sand, surface-treated with an silane or siloxane having the general formula: EQU R.sub.x SiX.sub.(4.sub.-x)
in which at least one R is an unsaturated group, preferably an unsaturated hydrocarbon group, e.g., an alkenyl, haloalkenyl or alkadienyl group, including dienyl, vinyl, chlorvinyl, bivinyl, allyl, methallyl, chlorallyl, and the like; X is a group which reacts with the hydroxyl groups present in sand or moisture normally present in the surface of sand such as, preferably, chlorine or bromine, although it may be oxyaryl, oxyalkyl, amino, etc.; x is a whole number from 1 to 3. If more than one R group is present, the remaining R groups can be hydrocarbyl, e.g., alkyl, such as methyl or ethyl or aryl, e.g., phenyl. Examples of these compounds are:
Allyl triethoxy silane PA0 Diallyl diethoxy silane PA0 Triallyl ethoxy silane PA0 Methallyl trichloro silane PA0 Trichloroallyl chloro silane PA0 Allylphenyl dichloro silane PA0 Allylethyl dichloro silane PA0 Allylmethyl diethoxy silane PA0 Diallylmethyl ethoxy silane PA0 Allyl trichloro silane PA0 Dimethallyl diethoxy silane PA0 Vinyl trichloro silane PA0 Divinyl dichloro silane PA0 Trivinyl monochloro silane PA0 Vinyl triethoxy silane PA0 Methyl vinyl dichloro silane in which the sand comprises at least 50% by weight of the coating composition.
The entire disclosures of U.S. Pat. Nos. 2,751,775 and 3,328,231 are hereby incorporated by reference and relied upon.
The coated masonry building units disclosed in said patents have surfaces that resemble ceramic tile finishes, yet have superior physical properties such as better mechanical strength, craze resistance, color uniformity, and resistance to staining.
These surfaces, while highly impervious to moisture, have been found to become discolored, whiten, when subject to long periods of storage in unprotected areas such as construction sites. This whitening (blushing) is the result of moisture absorption by the cured resin used in the facing composition.